Digitally controlled aspirator

ABSTRACT

A digitally controlled aspirator is provided with a processor that allows the user to select operating conditions including one or more default settings. The processor further includes sensors for sensing operational and environmental conditions and adjusts the operation of the aspirator to reflect the sensed conditions.

This application claims priority on U.S. Provisional Patent Appl. No.60/611,722, filed Sep. 21, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a medical aspirator and, more particularly, toa system that is microprocessor-controlled and methods of control andoperation therefor.

2. Description of the Related Art

Suction, or the application of a vacuum to a patient, has many useswithin medicine. It is used within the pre-hospital care, home care andhospital environments to help clear a patient's airway, to remove debrisfrom a surgical site, to provide gastrointestinal and wound drainage,and in some cases to help inflate a collapsed lung by providing mildnegative pressure in the pleural cavity. Because of diversity within thepatient population range (infant through adult) and the variety ofprocedures that are possible, each procedure has its own permissiblevacuum and airflow ranges, and as a result, almost all suction devicesare designed for a specific procedural use.

The usage environment has always dictated the types of suction apparatusthat are commonly used.

In the pre-hospital care environments the primary use of portabledevices is to provide relatively high vacuum and high airflow to theunprotected upper airway and to provide low vacuum and high airflow tothe protected airway. The home care environment requires electricallypowered devices that have adjustable vacuum (low to high) and highairflow for the removal of airway secretions as part of a patient'spulmonary toilet.

In the hospital environment a wide range of electrically powered suctiondevices is found. There are units whose performance is designed toprovide suction and flow to the upper airway as described above; unitsthat can provide high vacuum and high airflow to remove blood, bone andtissue debris from surgical sites; units that provide a mild vacuum andflow for drainage around wound sites; units that intermittently providemild vacuum and flow for drainage of the gastrointestinal tract; unitsfor draining the digestive tract; and units that provide low vacuum andhigh flow levels for pleural cavity evacuation. The required number ofeach type of suction apparatus is affected by seasonal patientpopulation changes and the patient composition existing within thesepopulations. This seasonal variability is quite common and results inmany hospitals having to rent additional devices to augment theirinventory.

Previous devices were limited in their ability to perform in more thantwo of the modes described above because their simple pneumatic controlslacked the ability to meet the flow, pressure and timing requirementsinherent in the various operating modes. If an economically viableaspirator were available that met the gamut of clinical requirements,then civilians and military providers would have a single unit thatmeets their clinical and mission needs. In addition, a need has alwaysexisted for a multi-function suction apparatus for military or otherremote pre-hospital or hospital applications.

Suction may be generated by pneumatic, manual power or electrical power.

Suction derived from manual power is generated when an operatorphysically causes a mechanical pump mechanism to be cycled back andforth. Manually powered suction devices produce irregular and difficultto control suction and are used almost exclusively in the emergencyenvironment. Not surprisingly, their use is restricted to emergencysuctioning of a patient's upper airway.

Suction derived from pneumatic power is generated when gas, flowing athigh velocity past an orifice (venturi), produces a vacuum at theorifice. This occurrence is commonly referred to as the BernoulliEffect. The amount of vacuum is controlled by increasing or decreasingthe flow of gas past this orifice which may negatively impact thedesired suction applied to the patient. This method typically usesoxygen as its source of gas power and is rarely used in the emergencyand hospital environments anymore due to the large amounts of oxygenthey consume. Pneumatically powered suction, when used, is limitedmostly to emergency suctioning of a patients upper airway.

Suction derived from electrically powered sources may obtain itsoperating power from alternating current (AC), or direct current (DC),or from a battery pack or fuel cell. Electrically powered suctiondevices use a motor driven vacuum pump or thermally-cycled mechanisms tocreate suction. The characteristics of the pumps will ultimatelydetermine the medical application to which they are applied.Electrically powered suction devices are the most common and are inwidespread use throughout the pre-hospital, home care and hospitalenvironments.

Designers have improved medical suction systems by incorporating smallerand/or more powerful pumps, state-of-the-art battery technology forportable variants and battery recharging technology related thereto, andvia the use of more sophisticated collection reservoirs (both disposableand reusable) that incorporate mechanical shut-off valves and filters(both bacteriostatic and/or hydrophobic). Control of suction devices hasbeen relegated to simple on/off switches and circuits, and vacuumlimiting mechanisms that consist of bleed-type valves that entrainambient air as a means by which to limit the vacuum applied to thepatient. The interface to these devices consists of simple indicatorssuch as illuminating lamps and/or mechanical vacuum gauges—typically ofthe bourdon-tube type.

In a few instances, designers have produced devices, capable ofproviding more than one mode of operation. The resultant devices areinvariably bigger, heavier, more complex, more prone to malfunction andpredicatively more expensive.

A very effective aspirator intended for use in ambulances is shown inU.S. Pat. No. 5,954,704. U.S. Pat. No. 5,954,704 is assigned to theassignee of the subject invention and the disclosure is incorporatedherein by reference.

SUMMARY OF THE INVENTION

The invention relates to an aspirator with a vacuum pump/motor assemblythat has a performance range sufficient to encompass the complete vacuumand airflow spectrum for all anticipated clinical uses, including thosedescribed above. Thus, the vacuum pump/motor assembly can be used toprovide suction and flow to help clear a patient's airway, to removedebris from a surgical site, to provide gastrointestinal and wounddrainage and to help inflate a collapsed lung by providing mild negativepressure in the pleural cavity.

The aspirator also may include a variable orifice valve that theprocessor uses to communicate with the vacuum pump for controllingvacuum levels. The processor preferably includes or communicates withone or more sensors for sensing vacuum pressure levels near the valve.

The aspirator also may include a motor speed control component and atachometer that the processor uses for controlling airflow. Theprocessor that instructs the motor speed control component to operate ata speed to generate an airflow based on an existing control setting forthe set operating mode. The tachometer component communicates measuredmotor speed information back to the processor. Motor speed determinesairflow rate. The processor then compares the information to determinewhether the set flow rate equals the measured flow rate. If the flow setdoes not equal the flow measured, the processor will adjust the signalto the motor speed control component for causing the motor to speed upor slow down accordingly.

The aspirator further includes controls that enable an operator to varythe performance of the aspirator in accordance with a particular medicaluse. The controls enable the operator to set the duration of the vacuumfrom a continuous vacuum to an intermittent schedule in accordance withthe needs of the particular medical procedure. The controls also enablethe operator to select vacuum pressure levels and flow rates.

The actual vacuum pressure level at the site of aspiration is dependenton factors other than the particular operational rate of the vacuumpump. For example, the load at the site of aspiration can vary inaccordance with conditions of a patient at any point in time. Powerlevels applied to the vacuum pump may be affected by local conditions,particularly when the aspirator is used at an emergency or non-hospitalsetting and when using a diminishing power source, such as a battery.The vacuum level also is dependent upon the altitude at which theaspiration is being carried out. In this regard, an aspirator often isused in a medical evacuation helicopter or in geographical locationssubstantially higher than sea level. Accordingly, the aspiratorapparatus of the subject preferably includes a closed loop feedbackcontrol. Thus, the operator may employ the control of the microprocessorto set a desired vacuum pressure level and airflow rate. The operatorthen may command the device to maintain this level and rate undervarious conditions. In a preferred embodiment, the apparatusautomatically compensates for altitude variations by adjusting theoperation of the vacuum pump in accordance with sensed changes inbarometric pressure so that a preset vacuum pressure level can bemaintained automatically.

The control of the aspirator preferably is achieved by a microprocessorthat communicates with the vacuum pump, the sensors and the controls.The microprocessor is operative to respond to signals from the controlsand the sensors and to modify the vacuum output of the vacuum pump tomeet a particular medical use.

The aspirator of the subject invention further includes output means foroutputting relevant information to the operator. The output meansprovides the operator with required operating information and maygenerate alarm signals under certain operating conditions. The outputdisplay preferably is operative to compensate for real time changes inambient atmospheric conditions, such as those changes that areattributable to altitude changes in a non-pressurized or partlypressurized environment.

The microprocessor of the aspirator preferably is preprogrammed withdefault settings for vacuum and airflow set points. The default settingspreferably conform to current clinical standards. Thus, the aspiratorcan be used immediately upon receipt by the operator without priorcalibration. However, the controls of the aspirator preferably enablethe operator to reconfigure a default setting based on the preference ofthe operator or based on local operating conditions.

The microprocessor may include an applications programming interface sothat the operator may configure the microprocessor. Additionally, theapplications programming interface enables the operator to requestcertain operational data and receive current status information based onthe requests. The interface may further be configured to permit remoteoperation and control. Additionally, the interface may permit aplurality of aspirators to be controlled by a single controller. As aresult, a single controller can provide input to several aspirators andcan receive current status information from a plurality of aspirators.

The operator controls preferably are simplified for ease of operation.In this regard, the controls may comprise a power switch. A rotaryencoder may be provided as part of or separate from the power switch.The rotary encoder enables an operator to select an operational mode oroperational settings from several optional parameters permitted by thelogic of the processor.

The controller may be operative to provide menu driven operatingprotocols. Thus, the user may select the appropriate mode of operationthrough a plurality of sequential command options. One selection of amode of operation may be followed by prompts that guide the user toselect safety defaults for protecting a patient from exposure to aninappropriate level of vacuum pressure or airflow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an aspirator in accordance with onepreferred embodiment of the subject invention.

FIG. 2 is a flow chart illustrating one preferred operational method ofthe subject invention.

FIG. 3 is a schematic illustration of a first preferred display providedby the LCD display of the apparatus.

FIG. 4 is a schematic illustration of a second preferred displayprovided by the LCD display of the apparatus.

FIG. 5 is a schematic illustration of a third preferred display providedby the LCD display of the apparatus.

FIG. 6 is a flow chart illustrating a preferred procedure for changingoperational modes, settings and defaults.

FIG. 7 is a schematic illustration of a fourth preferred displayprovided by the LCD display of the apparatus.

FIG. 8 is a schematic illustration of a fifth preferred display providedby the LCD display of the apparatus.

FIG. 9 is a schematic illustration of a sixth preferred display providedby the LCD display of the apparatus.

FIG. 10 is a schematic illustration of a seventh preferred displayprovided by the LCD display of the apparatus.

FIG. 11 is a schematic illustration of a eighth preferred displayprovided by the LCD display of the apparatus.

FIG. 12 is a schematic illustration of a ninth preferred displayprovided by the LCD display of the apparatus.

FIG. 13 is a schematic illustration of a tenth preferred displayprovided by the LCD display of the apparatus.

FIG. 14 is a schematic illustration of a eleventh preferred displayprovided by the LCD display of the apparatus.

FIG. 15 is a schematic illustration of a twelfth preferred displayprovided by the LCD display of the apparatus.

FIGS. 16A and 16B are schematic illustrations of a thirteenth preferreddisplay provided by the LCD display of the apparatus.

FIG. 17 is a flow chart illustrating preferred operations pertaining tothe triggering of the alarm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An aspirator in accordance with a preferred embodiment of the subjectinvention is identified generally by the numeral 10 in FIG. 1. Theaspirator 10 includes a suction apparatus 12, a processor 14, a powersupply 16 and a display 18. The apparatus 10 further include additionalinputs and outputs as explained further below.

The suction apparatus 12 includes a manifold 20 with a fluid inlet 22and a fluid outlet 24. A tube 26 is mounted to the fluid inlet 22 of themanifold 20 and communicates with a collection canister 27 disposedexternally on the aspirator 10 and connected to the suction apparatus12. The collection canister 27 in turn communicates with a hose and anappropriate suction catheter (not shown) that can be placed incommunication with the patient. The exact configuration of thecollection canister 27 and the suction catheter will vary in accordancewith the specific medical use for the apparatus 10 and may be of priorart design. In this regard, a known collection canister is shown in theabove-referenced U.S. Pat. No. 5,954,704.

The manifold 20 further includes a variable orifice electronic valve 30,such as a solenoid valve, that controls an air bleed between the fluidinlet 22 and the fluid outlet 24. The electronic valve 30 can adjust theamount of the air bleed over the range between a fully opened conditionand a fully closed condition. Additionally, the variable orificeelectronic valve 30 can be operative to open and close at a selectedfrequency or duty rate. Operation of the electronic valve 30 iscontrolled by the processor 14 as explained further herein. The manifold20 further includes a transducer 31 for sensing the negative pressurelevel at the manifold 20 and for generating a signal indicative of thevalue of the sensed negative pressure. The transducer 31 communicateswith the processor 14 as explained herein.

The suction apparatus 12 further includes a vacuum pump motor 32 thatcommunicates with a pump head 34. The pump head 34 in turn communicateswith the fluid outlet 24 of the manifold 20. The vacuum pump motor 32and the pump head 34 cooperate to generate a negative pressure when thesuction catheter becomes fully or partially occluded. The suctionapparatus 12 further includes a motor speed control and tachometer 36for controlling the operating speed of the vacuum pump motor 32 and forproducing an output signal to indicate the actual speed of the vacuumpump motor 32. The motor speed control and tachometer 36 communicateswith the processor 14. The motor speed control component receivesinformation from the processor 14 that tells it to generate an airflowbased on the current control setting for the set operating mode. Thetachometer component communicated information back to the processor 14and compares the information to see whether the flow set equals the flowmeasured. If the flow set does not equal the flow measured, theprocessor will adjust the signal to the motor speed control componentcausing the motor to speed up or slow down accordingly.

As illustrated herein, the vacuum pump motor 32, the pump head 34 andthe motor speed control and tachometer 36 are included in the housing 19of the suction apparatus 12. However, one or all of these components canbe disposed externally of the housing 19. For example, the vacuum pumpmotor 32 and the pump head 34 can be in the housing 19, while the motorspeed control and tachometer 36 can be in a separate external modulethat may include the processor 14. Alternatively, the vacuum pump motor32 and pump head 34 can be disposed externally of the housing 19 in aseparate motor housing. The motor speed control and tachometer 36 can bein the same motor housing, in the suction apparatus 12 or in theprocessor 14.

The processor (CPU) 14 of the aspirator 10 is in two-way communicationwith the suction apparatus 12 to provide a closed-loop feedback betweenthe suction apparatus 12 and the processor 14. In particular, processor14 has connections 38 to and from the variable orifice valve 30 andconnections 40 to and from the negative pressure transducer 28 in themanifold 20. The functional implications of the connections 38 and 40 aspart of the closed-loop control feedback is described further below.

The power supply 16 includes a connection 42 to a power input port 44 ofthe processor 14 so that the power supply 16 provides sufficient powerfor operating the suction apparatus 12, the processor 14, the display18, the motor speed control and tachometer 36, the vacuum pump motor 32and the variable orifice electronic valve 30. The power supply 16includes an internal power supply and power conditioning circuit 46connected to the power input port 44 via the connection 42. The powersupply 16 further includes a battery pack 48 connected to the internalpower supply and power conditioning circuit 46 for providing oneoptional power source. The power supply further includes an AC powersupply and battery charger unit 50 connected to an external power supplyand further connected to both the internal power supply and powerconditioning circuit 46 and the battery pack 48. A switch 52 is mountedto the power supply 16 and is operative for selectively switchingbetween an off mode, a battery power mode and an AC power mode. When theswitch is turned to the AC power mode, the AC power supply and batterycharger 50 supplies power to the battery pack 48 for recharging thebattery pack and further supplies power to the internal power supply andpower conditioning circuit 46 for powering the aspirator 10.

The display 18 preferably is an LCD display that is connected directlyto the processor 14. The display 18 is operative for displaying a broadrange of operating conditions as shown in FIG. 1 and as describedfurther herein. Additionally, the LCD display may be a touch sensitivedisplay that permits the operator to select sequential arrays of menuoptions as described below.

The processor 14 includes other inputs and outputs independent of thesuction apparatus 12, the power supply 16 and the display 18.Significantly, the processor 14 is connected to a barometric sensor 54that senses ambient barometric pressure conditions and providesbarometric pressure data to the processor 14 on a real time basis. Theprocessor 14 uses data from the barometric sensor 54 with data sensed bythe pressure transducer 31 to vary the operation of the variable orificevalve 30 and the motor speed controller 36.

The aspirator 10 further includes an alarm 56 connected to the processor14 and operative to produce an audible and/or visible alarm in responseto certain conditions input to the processor 14. For example, theprocessor 14 will trigger the alarm 56 in response to extreme ranges ofvacuum, a pump failure, a power failure or the like as illustrated inFIG. 1.

The processor 14 further includes a communication port 58, such as a USBor RS-232. The communication port 58 enables connection to a remotecontroller which can monitor and control the aspirator 10 from a remotelocation. Hence, a plurality of aspirators 10 can be controlled from asingle remote location, while each aspirator 10 provides real time dataat the communication port 58.

FIGS. 2-11 show one optional operating procedure for the aspirator 10.With reference to FIG. 2, a first step S1 of the procedure requires theoperator to actuate the switch 52 of the power supply 16 in FIG. 1 forsupplying power either from the battery pack 48 or the AC power supply50. The processor 14 then will perform a self check for the variouscomponents of the aspirator 10 as indicated schematically by step S2 inFIG. 2. As part of this step, the processor 14 will cause the display 18to display a screen image, such as the preferred image shown in FIG. 3.

Upon completion of the self check in step S2, the processor 14 willallow the operator to choose between operations with the previoussettings or with new settings as indicated at step S3. As part of thisstep, the processor 14 will cause the display 18 to display a screenimage, such as the preferred image illustrated schematically in FIG. 4.More particularly, the screen image will display the previousoperational mode (e.g., pharyngeal) and operational limits (e.g.,pressure level in mm of mercury and flow rate in liters per minute LPM).In many instances, the operator will choose to begin operations with theprevious setting, and the screen of FIG. 4 will be programmed toindicate acceptance of the previous settings. As a result, the user needmerely press the rotary encoder push button switch 60 shown in FIG. 1 toenter the “YES” selection. The process then will proceed to step S4 andto the operational start phase at input location J shown in FIG. 2. Inother instances, the operator will want to select a new operating modeor program. As noted above, the processor 14 initially will cause thedisplay 18 to display the acceptance of the previous settings. Thus, tochange the setting, the operator will turn the rotary encoder pushbutton switch 60 of FIG. 1. This will cause the “NO” image on thepreferred display of FIG. 4 to be illuminated. The operator then willpress the rotary encoder push button switch 60 so that the processor 14will direct the operator through the steps of selecting a new modeand/or program.

The processor 14 will lead the operator through a series of menu optionsfor selecting the appropriate mode and/or user program as indicated atstep S4. At this step, the processor 14 will cause the display 18 todisplay an image, such as the preferred image shown in FIG. 5. Theoperator then will turn the rotary encoder push button switch 60 untilthe appropriate operational mode is illuminated. The operator then willpush to rotary encoder push button switch 60 when the preferredoperational mode has been illuminated. One option provided by the screenof FIG. 5 is to select user programs distinct from the five optionaloperating modes of FIG. 5. Step S5 indicates the process step where theprocessor 14 determines whether the user programs option has beenselected. In those instances where the user programs are selected, theprocessor will proceed to step S6 as illustrated in FIG. 6. In thisstep, the processor 14 will cause the display 18 to identify theoptional user programs that can be changed or restored. A typical screenimage is illustrated in FIG. 7 and displays to the user the option ofchanging default mode, changing default settings, restoring factorysettings or exiting from the user programs option. The user will employthe rotary encoder switch 60 until the processor 14 causes the display18 to illuminate the selected program option.

Step S7 identifies a step where the processor 14 determines whether theoperator has selected a change in the default mode. If this change hasbeen selected, the processor 14 will proceed to step S8 to permit theoperator to select the new default mode or to “exit” if the operatordetermines that the existing default mode is acceptable. FIG. 8 shows anoptional preferred screen display that will permit the operator toselect a new default mode or to exit from this user program option. Onceagain, the operator will use the rotary encoder push button switch 60 tochoose the appropriate option in FIG. 8 and then to confirm thatselection.

The processor 14 will require the operator to confirm the selection madein step S8. This confirmation step is a fail safe procedure and isillustrated by step S9 in FIG. 6. If the user chooses in step S9 not toaccept the new default mode, the processor 14 will return the operatorto step S8 for selecting a new default mode or for exiting from thisoption. If the user chooses in step S9 to exit from this changingdefault mode option, the processor 14 will return the operator to stepS6. If the user chooses in step S9 to accept the new default mode thenthe processor 14 will direct the user to steps for selecting defaultsettings for the selected default mode as explained below.

The operator, in step S7, may choose not to change the default mode.Under these conditions, the processor will determine in step S10 whetherthe operator wants to change the default settings. The operator willindicate a desire to change the default setting by rotating the rotaryencoder push button switch 60 until the change default setting has beenidentified, such as in the preferred screen image shown in FIG. 7. Theoperator then will press the rotary encoder push button switch 60. Underthese conditions, the processor will proceed to step S11. FIG. 6 alsoshows that step S11 will be reached under those conditions where theoperator has chosen to accept the new default mode in step S9. Theprocessor 14 will cause the display 18 to display the optional defaultsettings as illustrated in the preferred screen image of FIG. 9. Theoperator then will use the rotary encoder push button switch 60 forchoosing each of the optional settings. One of the optional settingsshown in FIG. 9 is “Exit” which will be selected if the operator hasdetermined that a different user program option should have beenselected. After making the selections offered by FIG. 9 and as part ofstep S11, the processor will require the operator to confirm the newdefault settings, as illustrated in step S12. One option is for theoperator to exit this decision making step. In response to a selectionof the exit option, the processor 14 will direct the user back to stepS6 for selecting one of the optional programs. Alternatively, theoperator could choose not to accept the default settings in step S12.Under this selection, the processor 14 will return the operator to stepS11 and FIG. 9 so that the operator can choose new default settings orexits from this decision process. Of course, step S12 permits theoperator to accept the new default settings. Under these circumstances,the processor 14 will proceed to a step for restoring factory defaults.The processor 14 will proceed to determine whether the operator haschosen to restore the factory defaults.

The operator may choose in step S10 not to change the default settings.As a result, the processor then will determine in step S13 whether theoperator chooses to restore the factory default settings. This preferreddecision making screen is illustrated in FIG. 10, and the operator isgiven the option of either exiting or restoring the factory defaultsettings. An operator who chooses to restore factory defaults will bedirected by the processor to step S14 and to the preferred screen imageshown in FIG. 11. The processor then will direct the operator in stepS15 to either accept the factory default setting or to exit from thisdecision making process. An operator who chooses to exit from step S15will be directed back to step S6 and to the preferred screen of FIG. 7.A user who chooses to accept the factory default settings in step S15will be given an option in step S16 to either exit from this decisionmaking process or to return to the selection of user programs describedabove with respect to step S6-S15. A user who chooses not to exit thisdecision making process will be returned to step S6. An operator whochooses to exit will be returned to the primary process of FIG. 2 atinput location H.

An operator who has chosen not to select user programs or who hascompleted the selection of user programs, as outlined above and shown inthe preferred screen images of FIGS. 6-11, will be directed by theprocessor 14 to step S17 in FIG. 2. In step S17, the processor 14 willdisplay the current setting with a screen display similar to thepreferred screen display of FIG. 12. The processor 14 then will give theoperator the option in step S18 of choosing whether to accept thecurrent settings. An operator who chooses to accept the current settings(step S19) will be directed to input J for commencing the operation ofthe aspirator 10. An operator who chooses in step S18 and in FIG. 12 notto accept the current settings will be directed to step S20 by theprocessor 14. The processor 14 also will cause the display 18 to displayan image such as the preferred image of FIG. 13 as part of step S20. Theoperator then will use the rotary encoder push button switch 60 with theFIG. 13 display to make changes to the current settings. The processor14 then will require the operator in step S21 to affirm the acceptanceof the changed current settings. An operator could choose to exit (FIG.14) this part of the decision making and will be returned to step S19and then to input location J for starting the operation of the aspirator10. An operator could choose in step S19 not to accept the changes (FIG.14). Under these conditions, the processor 14 will direct the operatorback to step S20 for further changing the current settings. However, theprocessor 14 further will give the operator the option in step S21 andFIG. 14 to accept the changes. The processor 14 then will direct theoperator to step S22 and onto the start of operations as indicated atstep S23. The operator also will be directed to step S23 (via input J)if the operator had chosen in step S4 to begin operations with theprevious setting or if the operator had chosen in step S19 to begin orcontinue operations with the current settings.

The processor 14 will cause the display 18 to display operating screensas shown, for example, in FIGS. 16A and 16B. The version of theoperating screens shown in FIGS. 16A and 16B will be displayed and willvary in accordance with sensed operating conditions throughout theentire operation of the aspirator 10.

The operation indicated generally by step S23 normally will continue fora considerable time and can be monitored on the display, as shown inFIGS. 16A and 16B. However, the operation may be interruptedintentionally by the operator or due to unintended operating conditions.This interruption of the operation at step S23 is assessed by theprocessor 14 at step S24. More particularly, an operator may determinethat operational settings need to be changed. Under these conditions,the operator will press the rotary encoder push button switch 60 twicein succession. This double pressing of the switch 60 identified in stepS24 will cause the processor to proceed to step S25 and to the preferredscreen image shown in FIG. 15. The operator then uses the rotary encoderpush button switch 60 of FIG. 1B to choose a new mode (step S26) vacuum,airflow, on/off time parameter (step S27) or exit (step S28). Anoperator who chooses in step S26 to select a new mode will be directedby the processor 14 to input location B and step S4. An operator whochooses to select a new setting of vacuum, airflow, on/off time in stepS27 will be directed by the processor 14 to input location C and stepS20 as described above. An operator who chooses in step S28 to exit willbe directed by the processor to input location D and step S19 andfurther to input location J as described above for beginning theoperation.

If the operation of step S23 is interrupted and if step S24 determinesthat the encoder 60 was not pressed twice, the processor 14 willdetermine whether the alarm 56 has been actuated. If the alarm 56 hasnot been actuated, the processor will return to step S23 to continueoperation. If the processor 14 determines in step S29 that the alarm hasbeen actuated, the processor 14 will proceed to input location K shownin FIG. 17. FIG. 17 shows the preferred logic employed by the processor14 to determine the reason for the alarm. In step S30, the processor 14will determine whether the battery is low or has failed. If the batteryis low, the processor in step S31 will cause the display 18 to advisethe operator that the alarm can be muted and to advise the operator asto conditions that should be undertaken to address the low batterycondition. The processor 14 determines in step S32 whether the alarm 56has been muted. If the alarm 56 has not been muted, the audible andvisual alarm signals will remain active as indicated by step S33. If thealarm 56 has been muted as determined in step S32, then the display willinclude an icon in step S34 confirming that the alarm has been muted. Apredetermined mute period is programmed in the processor 14. In stepS35, the processor 14 will determine whether the mute period has ended.If the mute period is continuing, as determined in step S35, theprocessor 14 will ensure that the message of step S34 continues to bedisplayed. If the mute interval has elapsed, as determined in step S35,the processor 14 will return to step S30.

The processor 14 may determine in step S30 that the battery is not low.Under this condition, the processor will continue to step S36 fordetermining whether external power is low. If the processor 14determines in step S36 that the external power is low, then theprocessor will proceed to steps S37-S41 which substantially parallel thesteps S31-S35 as described above. If the processor 14 determines in stepS36 that the external power is not low, then the processor will proceedto step S42 for determining whether the external power has failed orbecome disconnected. The processor 14 will proceed to step S43 if adetermination has been made that the external power has failed or hasbecome disconnected. More particularly, step S43 will give the operatorthe option of canceling the alarm message. The status of the alarm 56 isassessed in step S44. Here the processor will return to step D of FIG. 2if the alarm has been canceled. Thus, the processor 14 will continuethrough the operation, as indicated at input location J and step S23. Onthe other hand, the external power fail/disconnect alarm message willcontinue at step S45 if the operator has not canceled the alarm 56 instep S44.

The portion of FIG. 17 from steps S30 through steps S45 assume thatexternal power can be supplied or restored or a new battery can beactivated so that the operation of step S23 can proceed. However, thealarm sensed in step S29 may be attributable to other causes. Hence, ifthe alarm 56 is sensed in step S29 and is not attributable to powerrelated issues of steps S30, S36 and S42, the processor 14 will proceedto steps S46-S49 sequentially. In particular, step S46 determineswhether a high vacuum condition exists. This may be determined by inputreceived by the processor 14 from the closed loop control feedbacksignal and control lines 38 and 40 that connect the processor 14 to thevalve 30 and the transducer 31. The determination in step S46 that ahigh vacuum exists will cause the processor 14 to transmit a signal todisplay 18 for displaying a high vacuum message. Additionally, audibleand visual alarm signals remain active and cannot be muted. Furthermore,the processor 14 will cease operation of the aspirator 10. This problemcan be cleared by recycling the on/off switch 52. However, furtherservice may be required if the condition persists.

Step S47 determines whether the pump motor 32 has failed. Thisdetermination may be made by the connection 37 of the closed loopcontrol signals in the control lines to and from the processor 14 andthe motor speed control and tachometer 36. Once again, a sensed pumpfailure in step S47 will cause the operation to cease. Power can berecycled by operating the switch 52. However, service may be required ifthe pump failure persists, and in this circumstance, the display 18 willindicate the need for such service. As with the high vacuum conditionsensed in step S46, the pump failure sensed by step S47 does not permita muting of the alarm.

Step S48 determines whether the self check of step S2 in FIG. 2 hasoccurred. The determination in step S48 that the start-up self check hasfailed will cause operation to cease. The alarm 56 cannot be muted andthe operation is not allowed. Display 18 will display an appropriateservice message.

Step S49 determines whether there is a system failure that is notaddressed by any of steps S30, S36, S42, S46, S47 or S48. Operation willcease if a system failure is sensed. However, a determination in stepS49 that there is no system failure will cause the processor to commenceoperation again at input location J and step S23.

The preceding paragraphs describe optional ways for changing settingsusing the processor 14. It should be understood, however, that theaspirator 10 continues to operate at its current setting until a changehas been accepted. Furthermore, a change in a setting may be initiatedbut not completed for any number of reasons. Accordingly, the processoris programmed to return the screen to its previous setting image (e.g.,FIGS. 16A, 16B) if there is a pause in the setting change greater thanthe pre-programmed amount of time.

While the invention has been described with respect to a preferredembodiment, it is apparent that various changes can be made withoutdeparting from the scope of the invention as defined by the appendedclaims. For example, the apparatus and process has been described withrespect to user input from a rotary encoder push button switch 60.However, a touch screen input can be provided as well. Of course, thescreen images illustrated herein are only preferred examples, and manyother screen images can be developed to convey similar information andto trigger similar decision making processes. Additionally, the userinput can be provided from a remote location and may include inputprovided from the keyboard of a computing device.

1. An aspirator comprising: a vacuum pump for producing a vacuumpressure; a motor for driving the vacuum pump; a manifold having adownstream side in communication with the vacuum pump and an upstreamside for communicating with a patient; a valve communicating with themanifold and being operable for controlling vacuum characteristicsacross the manifold; a sensor in communication with the manifold forsensing actual vacuum pressure characteristics across the manifold; anda processor for controlling at least one of the motor and the valve foraltering at least one of the actual vacuum pressure across the manifoldor airflow through the manifold to achieve at least one operationalcharacteristic specified by the processor.
 2. The aspirator of claim 1,further comprising a barometer for sensing ambient atmospheric pressure,the processor being connected to the barometer and further beingoperative for controlling at least one of the motor and the valve inview of ambient atmospheric pressures.
 3. The aspirator of claim 1,wherein the processor is operative for controlling both the motor andthe valve for altering both the actual vacuum pressure across themanifold and the airflow through the manifold.
 4. The aspirator of claim1, further comprising an alarm connected to the processor and operativeto generate an alarm signal in response to at least one failure modesensed by the processor.
 5. The aspirator of claim 4, further comprisingat least one power source for powering the processor, the motor and thevalve, the alarm being operative to produce an alarm signal in responseto at least a partial power failure.
 6. The aspirator of claim 5,wherein the power source comprises a battery and wherein the alarmproduces an alarm signal in response to a failing battery.
 7. Theapparatus of claim 6, wherein the power source further comprises meansfor connection to a supply of AC power, the alarm being operative togenerate an alarm signal in response to at least one of a low externalpower level, an external power failure and an external power disconnect.8. The aspirator of claim 4, wherein the processor is operative tocompare actual vacuum pressure sensed by the sensor to a maximumallowable vacuum pressure level and to terminate operation of theaspirator in response to an actual vacuum pressure at least equal to themaximum allowable vacuum pressure.
 9. The aspirator of claim 1, whereinthe processor further includes at least one operator input switch forpermitting an operator to select at least one of the specifiedoperational characteristics.
 10. A method for providing medicalaspiration, said method comprising: providing an aspirator having avariable controllable vacuum pump for producing a vacuum pressure and anairflow, the aspirator further having a valve for controlling thevacuum; selecting a specified airflow rate and a specified vacuumpressure; measuring an actual airflow rate and an actual vacuum pressureacross the valve; comparing the specified airflow rate to the actualairflow rate; comparing the specified vacuum pressure to the actualvacuum pressure; and automatically adjusting at least one of the vacuumpump and the valve for conforming the specified and actual airflow ratesand the specified and actual vacuum pressures.
 11. The method of claim10, further comprising measuring ambient atmospheric pressure andadjusting the vacuum pump to compensate for variations in ambientatmospheric pressure.
 12. The method of claim 10, further comprisingdelivering power to the vacuum pump from a power source; measuring thepower level from the power source; and adjusting at least one of thevacuum pump and the valve in response to a change in the power level.13. The method of claim 12, further comprising generating an alarmsignal in response to certain sensed conditions.